4-5 mph depending on wind, tides etc..
8-15
50 mph
Depends on how it is geared.
70
25 or so I would guess. My tri cruiser with 90hp Honda goes 23.
25-40
A 3HP motor can reach speeds up to at least 30 mph depending on what you are using it for.
about 25-30 mph
25 HP is 25 HP, no matter how you slice it and dice it.
About 10 to 12 on plane
To change a 15 hp motor into a 25 hp motor, you would need to replace the motor entirely with one that is rated for 25 hp, as simply modifying the existing motor is not feasible or safe. Upgrading to a higher horsepower motor involves ensuring that the electrical supply, drive components, and mechanical systems can handle the increased power. Additionally, you must consider the motor's cooling requirements and mounting compatibility in the system. Always consult with a qualified engineer or technician for such modifications.
Johnson produced a 25 hp outboard motor from 1973 to 1985. This model was popular among recreational boaters for its reliability and performance. The 25 hp motor was part of Johnson's broader lineup of outboard engines during that period.